In the late 1980s, Oneida and Herkimer counties of New York faced a solid waste crisis due to mismanagement of their landfills and other waste disposal sites. Several existing landfills were shut down, and the two counties formed the Oneida-Herkimer Solid Waste Management Authority (OHSWMA) (defendant), a public benefit corporation, to collect, process, and dispose of solid waste in the counties. In 1989, the counties and the OHSWMA entered into an agreement where the OHSWMA would exclusively manage all processing of waste generated in the counties. The OHSWMA collected tipping fees from each load of waste processed to help fund its operations. To avoid the tipping fees certain citizens attempted to send their waste to out-of-state waste processors. In response to this, the OHSWMA passed “flow control” ordinances, which required all waste produced within the counties be delivered to OHSWMA’s processing sites. In 1995, United Haulers Assn., Inc. (plaintiff), a trade association made up of solid waste management companies operating in the two counties, sued the OHSWMA on the grounds that the flow ordinances violated the Commerce Clause because they discriminated against interstate commerce. United Haulers introduced evidence that without the laws, they could dispose of waste in out-of-state sites for significantly cheaper costs than waste disposed of in the OHSWMA’s sites. The district court ruled in favor of United Haulers Assn, Inc., but the court of appeals reversed. The United States Supreme Court granted certiorari.